X10CrMoVNb9-1 / 1.4903

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X10CrMoVNb9-1 / 1.4903

, , , Plate: A/SA 387 gr 91.
Round steel: A/SA 182 F91.
Pipe: A/SA 335 P91
1.4903 650°C

X10CrMoVNb9-1, also known as 1.4903 is an alloy martensitic pressure vessel steel. The material is designed to be a heat-resistant steel that provides high creep resistance. The steel also has an increased impact strength.

The low carbon content gives the steel properties that are particularly suitable for both mechanical processing and welding. 1.4903 is a material used in applications where conventional heat-resistant steels cannot meet the requirements.

This type of steel is often used in high temperature applications such as power plants, chemical plants and oil refineries due to its excellent resistance to oxidation, creep and high temperature strength.

Overall, steel 1.4903 is a high performance material well suited for use in extreme temperature and pressure environments.

Dimension Sheet / Plate6 - 60 mm
Dimension RoundbarØ 20 - 700 mm
Yield strengthmin. 450 N/mm²
Tensile strength580 - 760 N/mm²
Impact test+20°C / 40J
AImin. 0,040
C0,08 - 0,12
CR8,00 - 9,50
Cumax. 0,30
Mn0,30 - 0,60
Mo0,85 - 1,05
N0,030 - 0,070
Nb0,06 - 0,10
Nimax. 0,30
Pmax. 0,020
Smax. 0,005

Classified alloyed boiler steel from Livallco

At Livallco, we are one of the few steel wholesalers in the world to stock 1.4903 material. We stock X10CrMoVNb9-1 in thickness 6-50 mm. Our plate is always delivered with classification according to national standards:

  • EN 1.4903 / X10CrMoVNb9-1 / ASTM A 387 / ASME SA 387 / Grade 91
  • EN 10160 S2/E3 and ASTM A57 (ultrasonic tested).

Do you have questions about our steels? Welcome to contact us and we will help you further!


X10CrMoVNb9-1 has several applications in various types of heavy industry. The steel is designed to withstand creep resistance at high working temperatures of up to 600 °C.

Common uses and applications include:

  • steam piping and pipe support systems in power generation processes
  • heavy section components in thermal power plants
  • pressure vessel applications for refining and in nuclear power plants
  • various types of steam boilers
  • valve systems in the gas and oil industry.

Manufacturing and properties

In the manufacture of 1.4903, it is desired that the material is particularly pure, homogeneous and reproducible. The pressure vessel steel is produced in furnaces with processes such as LD converters.

During production, it is ensured that the final steel produced can withstand welding, high creep strength and impact resistance in heat-affected zones. It also gains high resistance to hydrogen attack. Compared to standard stainless steels, 1.4903 has a lower tendency to be activated by irradiation.


Are you looking for other types of alloyed boiler steel?

Livallco stocks a wide range of both alloy and non-alloy pressure vessel steels.  Check out our full range or contact us if you have any questions.